Figures to reveal swine flu spread
The number of new swine flu cases in England is set to be released.
The Department of Health's weekly update is also likely to include GP consultation rates which rose sharply over the last month in England.
The latest results showed Tower Hamlets, in east London, was the primary care trust with the highest number of GP consultations for people with flu-like illness.
Recent research showed pregnant women with swine flu are four times more likely to be admitted to hospital than members of the general population.
The findings from the US suggest pregnancy places women at extra risk of serious complications from the virus.
Experts from America's leading public health body said it reinforced the need to treat infected pregnant women with antiviral drugs "as soon as possible".
The new research was carried out by the US Centres for Disease Control and Prevention (CDC), the American equivalent of the UK Health Protection Agency and published in The Lancet medical journal.
Latest Health Protection Agency figures show that, in the week ending July 19, an estimated 100,000 Britons were infected with swine flu - almost double the tally for the previous week.
There have been a total of 26 confirmed deaths in England linked to swine flu. Children under 15 accounted for a third of deaths, while around one in seven victims was previously in good health. At the last count, 840 flu patients were being treated in hospital in England, with 63 in intensive care.
More than 700 people worldwide are known to have died after getting swine flu which the World Health Organisation says is spreading faster than any previous flu pandemic.